common\models\User::isPasswordResetTokenValid PHP Method

    public static function isPasswordResetTokenValid($token)
    {
        if (empty($token)) {
            return false;
        }
        $timestamp = (int) substr($token, strrpos($token, '_') + 1);
        $expire = Yii::$app->params['user.passwordResetTokenExpire'];
        return $timestamp + $expire >= time();
    }

 public function sendMail()
 {
     /* @var $user User */
     $user = User::findOne(['status' => User::STATUS_ACTIVE, 'email' => $this->email]);
     if ($user) {
         if (!User::isPasswordResetTokenValid($user->password_reset_token)) {
             $user->generatePasswordResetToken();
         }
         if ($user->save()) {
             $setting = Setting::find()->where(['id' => 1])->one();
             $username = $setting->sendgridUsername;
             $password = $setting->sendgridPassword;
             $mail_admin = $setting->emailAdmin;
             $sendgrid = new \SendGrid($username, $password, array("turn_off_ssl_verification" => true));
             $email = new \SendGrid\Email();
             $mail = $user->email;
             //echo $user->email;exit(0);
             $resetLink = \Yii::$app->urlManager->createAbsoluteUrl(['site/reset-password', 'token' => $user->password_reset_token]);
             $body_message = 'Hello ' . Html::encode($user->username) . ', <br>
             Follow the link below to reset your password:  <br>
             ' . Html::a(Html::encode($resetLink), $resetLink);
             $email->addTo($user->email)->setFrom($mail_admin)->setSubject('Password reset for ' . \Yii::$app->name)->setHtml($body_message);
             $response = $sendgrid->send($email);
             return $response;
         }
     }
     return false;
 }